Ruttler Mills PLLC

Seattle Patent Attorneys and Trademark Lawyers

Claim Construction

Posted Friday, October 18, 2013 by Brian Apel

In 1995, the CAFC decided and the Supreme Court affirmed the landmark Markman case that held that in the context of patent infringement lawsuits, determining the meaning of claims, i.e. “claim construction,” is a question of law to be decided by judges not juries. Hearings on claim construction are frequently called Markman hearings. This relatively new process is proving to be challenging for the CAFC and the district courts.

Shortly after Markman, in Vitronics, the CAFC provided some clarity for the district courts in how claim construction is to be accomplished. For reasons of public disclosure, fairness, and competition, intrinsic evidence is to be examined first (e.g. the words of the claims, the specification, and the prosecution history) before considering extrinsic evidence such as dictionaries and expert testimony.

In 2002, in response to the CAFC’s concern that district courts were reading limitations from the written description into the claims, it suggested in Texas Digital that, while intrinsic evidence is still to be given priority, district courts were free to use extrinsic evidence such as dictionaries at any point to assist in construing disputed claim terms. It was thought that using dictionaries both to better understand the technology and to properly understand claim terms would prevent the district courts from improperly limiting patent claims.

Three years later, it appears the CAFC believed the pendulum swung too far and that claims were being construed too broadly due to district courts’ overreliance on dictionaries. In 2005 in Phillips v. AWH Corporation, the CAFC backpedalled slightly from Texas Digital but reiterated their guidance from Vitronics. They emphasized that intrinsic sources, specifically the specification and written description, remain the best sources for construing disputed claim terms. Thus, courts should not consult dictionaries first and then “confirm” their definition with the specification. Rather, courts should look to the claim terms themselves, the specification, and the prosecution history first.While appearing to hold fast to their original guidance, the challenges the CAFC faces with these new Markman hearings are clear. How they all will be resolved remains to be seen.